scsi: megaraid: make two symbols static in megaraid_mbox.c

Fix the following sparse warning:

drivers/scsi/megaraid/megaraid_mbox.c:305:5: warning: symbol
'dev_attr_megaraid_mbox_app_hndl' was not declared. Should it be static?
drivers/scsi/megaraid/megaraid_mbox.c:315:5: warning: symbol
'dev_attr_megaraid_mbox_ld' was not declared. Should it be static?

Link: https://lore.kernel.org/r/20200407092827.18074-2-yanaijie@huawei.com
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/megaraid/megaraid_mbox.c

@@ -302,8 +302,8 @@ static struct pci_driver megaraid_pci_driver = {
 // definitions for the device attributes for exporting logical drive number
 // for a scsi address (Host, Channel, Id, Lun)
 
-DEVICE_ATTR(megaraid_mbox_app_hndl, S_IRUSR, megaraid_sysfs_show_app_hndl,
-		NULL);
+static DEVICE_ATTR(megaraid_mbox_app_hndl, S_IRUSR, megaraid_sysfs_show_app_hndl,
+		   NULL);
 
 // Host template initializer for megaraid mbox sysfs device attributes
 static struct device_attribute *megaraid_shost_attrs[] = {
@@ -312,7 +312,7 @@ static struct device_attribute *megaraid_shost_attrs[] = {
 };
 
 
-DEVICE_ATTR(megaraid_mbox_ld, S_IRUSR, megaraid_sysfs_show_ldnum, NULL);
+static DEVICE_ATTR(megaraid_mbox_ld, S_IRUSR, megaraid_sysfs_show_ldnum, NULL);
 
 // Host template initializer for megaraid mbox sysfs device attributes
 static struct device_attribute *megaraid_sdev_attrs[] = {